Not Applicable
Not Applicable
1. Field of Invention
This invention pertains to optical fiber switches for switching optical transmission paths. More particularly, this invention pertains to a fiber optic switch which can switch between incoming optical transmission paths based upon the quality or condition of the signal being transmitted.
2. Description of the Related Art
Optical fibers are commonly used for the transmission of all types of data, including telecommunications, video, and computer data. Fiber optic cables have become an alternative to conventional wire transmission. The advantages of fiber optic cables over wire include greater bandwidth over greater distances with less loss and less cost. Fiber optic cables are considerably less susceptible than metal conductors to unauthorized xe2x80x9ctapsxe2x80x9d and eliminate R.F. problems and the need for electrical isolation interfaces such as opto-isolators. Because of these advantages, fiber optic cables often are used as an alternative to wire in networks.
Typically, fiber optic cables are used to form a transmission line from an origination point to a destination point. Because of the great bandwidth of optical fiber, many times the fiber optic cable transmits in both directions, so that the origination point for one direction is also the destination point. Depending upon the length of the transmission line, lengths of fiber optic cable may have to be spliced, and the optical signal may have to be amplified in order to maintain the signal strength at the destination point. Along the transmission line, taps and routers may be used so that either portions of or all of the optical signal can be delivered to multiple destinations. Because of their widespread use, fiber optic networks oftentimes have complex topologies and numerous components, and accordingly, are subject to various faults. These faults may develop over a period of time and be evidenced by a slow degradation of signal quality and strength, as in dirt and grime accumulating at connection points and obstructing the cable""s optical interface. Other faults may be catastrophic and occur suddenly, as in a cable being cut by an outside force or by failure of an upstream device.
There is a need to provide fast, intelligent fault recovery when a fiber optic cable no longer carries a signal. Fault recovery needs to occur with little delay because with a great bandwidth, long out-of-service times result in the loss of a great amount of data and information.
Therefore, it is an object of the present invention to provide a means for automatically switching between fiber optic cables.
It is a further object of the present invention to sense conditions on multiple fiber optic cables and perform the switching based on the sensed condition.
It is a still further object of the present invention to provide rapid switching such that minimum disruption occurs.
Another object of the present invention is to provide a means for preventing the switch from switching too frequently or oscillating between optical signal inputs.
Still another object of the present invention is to provide for remote control and monitoring of the switching.
According to a preferred embodiment of the present invention, a network healing smart fiber optic switch assembly is disclosed comprising an optical switch responding to a controller which monitors multiple paths of an optical transmission line. Each fiber optic input is split into two signal paths, one a primary path and containing a majority of the signal strength and the other a secondary path for sensing. Each primary path goes to the optical switch and each secondary path goes to the controller, which senses the quality or condition of each fiber optic input. A fault on the primary fiber optic cable causes the network healing smart fiber optic switch to switch to another fiber optic cable within a selected amount of time and preferably within 10 milliseconds. Faults on a fiber optic cable are defined as a degradation of signal strength below a threshold level or the complete loss of the optical signal. The network healing smart fiber optic switch is also controlled locally and remotely via a buss connection with another computer or controller.